On Sat, 3 Apr 2021 at 16:05, Andrey Konovalov <andreyknvl@xxxxxxxxx> wrote: ... > Which kasan_byte_accessible() call fails? > > KASAN checks shouldn't be performed for KFENCE objects. We have a > number of is_kfence_address() checks in KASAN runtime, but maybe we're > missing some. Perhaps, we should even move those checks into the > high-level wrappers in include/linux/kasan.h. Moving them into include/linux/kasan.h seems unnecessary and an easy way to introduce unnecessary overhead. AFAIK, there should be no difference between having them in the high-level wrappers and the inner runtime functions. I think until we understand what is actually going on and could thoroughly justify, I'd be opposed to larger changes. The small patch here is innocent enough, but it'd still be good to understand. (FWIW, I believe the issue was encountered with SW_TAGS on a downstream kernel.)
